This application claims the benefit of Korean Patent Application No. 2002-7707, filed on Feb. 9, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to the field of silicon light-receiving devices, and more particularly, to a silicon light-receiving device having a high quantum efficiency due to a quantum confinement effect.
2. Description of the Related Art
FIG. 1 is a schematic diagram of a solar cell as an example of a silicon light-receiving device. Referring to FIG. 1, a general solar cell has a p-n diode structure in which an n-type semiconductor 1 and a p-type semiconductor 2 are joined to obtain and utilize a photovoltaic effect by which light energy is converted into electric energy. Electrodes 3 and 4 for connecting an external circuit to the n- and p-type semiconductors 1 and 2 are formed on the upper surface of the p-type semiconductor 2 and the bottom surface of the n-type semiconductor 1, respectively.
Referring to FIG. 2, when light is incident upon the p-n diode structure of FIG. 1 and a photon is absorbed into it, a pair of an electron 7a and a hole 7b is generated at both sides of a p-n junction. At this time, the electron 7a moves toward the n-type semiconductor 1 and the hole 7b moves in the opposite direction. Accordingly, when the load resistor 5, which is an external circuit, is connected to the p-n diode structure, according as light energy is converted into electric energy, current I flows through the p-n diode structure.
Typically, silicon is used as the semiconductor material for solar cells as described above. The solar cells having a diode structure using silicon semiconductors provide a low efficiency when converting light energy into electric energy. In theory, single crystal silicon has about 23% photoelectric conversion efficiency, polycrystal silicon has about 18% photoelectric conversion efficiency, and amorphous silicon has about 14% photoelectric conversion efficiency. During actual operation of solar cells using one of the aforementioned types of silicon as semiconductor materials, the photoelectric conversion efficiency decreases more.